Pneumatic tool



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D. DRAWBAUGH.

PNBU-MATIG TOOL. No. 472,495. Patented Apr. 5, 1892.

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(No Model.)

D. DRAWBAUGH.

PNBUMATIG TOOL.

No. 472,495. Patented Apr. 5,' 1892.

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UNITED STATES PATENT OFFICE.

DANIEL DRAWBAUGH, OF EBERLYS MILL, PENNSYLVANIA.

PN EU MATIC TOOL.

' SPECIFICATION forming part Of Letters Patent NO. 472,495, dated April 5, 1892. Application filed December 7, 1891l Serial No. 414,291. (No model.)

To @ZZ whom it may concern:

Be it known that I, DANIEL DEAWBAUGH, of Eberlys Mill, in the county of Cumberland and State of Pennsylvania, haveinvented certain newand useful Improvements in Pneumatic Tools; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming a part of this specification, and to the letters of reference marked thereon.

This invention relates to that class of tools ordinarily operated by compressed air or similar elastic gas and adapted to strike a series of blows with great rapidity, the force of which is utilized in stone planing, carving, and various kinds of metal working, such as boiler-calking, repousse work, dac.; and the objects of the invention are to improve and simplify the construction, whereby the initial cost is reduced, the lateral vibration lessened, the diameter of the tool reduced, and the general efliciency increased.

Broadly stated, the invention may be said to consist, primarily, in arranging the cylinder and valve-chest with their longitudinal centers substantially inalign ment and within an integral casing.

Further than this, the invention consists in certain novel details of construction and com` binations and arrangements of parts to be now described, and pointed out particularly in the appended claims.

Referring to the accompanying drawings, y

Figure l is an elevation of a tool constructed in accordance with my present invention. Fig. 2 is a longitudinal vertical section taken through the pressure and exhaust passages. Fig. 3 is a similar view at right angles to Fig. 2, showing the passages from the valve to each end of the cylinder. Fig. 4. is a sectional perspective of the casing. Fig. 5 is a perspective view of the piston and outside of the bushing for the valve-chest. Fig. 6 is asimilar view showing the ports and passages on the opposite side.

Like letters of reference in the several figures indicate the same parts.

The preferred construction of tool in the present instance has the usual casing or bodysection A, to which are screwed the cap-piece B and the point-section C, the latter carrying the tool-stock O', constructed in the usual or l any preferred manner, and as it forms no part ing D, with a solid lower end and a removable plug CZ at the upper end, and suitable ports and passages, to be presentlydescribed. The valve itself is a pressure or steam-actuated one, and the pressure to and exhaust from its opposite ends are controlled by the piston, the passages for this purpose being formed in the walls of the casing, but the pas'- sages for the pressure and exhaust from o/pposite ends of the cylinder are formed almost entirely in the valve-bushing or piston itself. Thus as the passages controlling the valve are small the diameter of the tool may be greatly reduced, and the largest size may be made of such proportion as to be easily grasped by the operator.

Compressed air or pressure is admitted through the cap-piece B, to which the supplypipe is attached, as usual, and from the upper end of the bushingD on the outside thereof is formed a passage F, which will be called the live-pressure passage, and fromwhich two ports ff open into the interior of-the bushing in position to be brought alternately into communication with the ports f f 2 (leading, respectively, to opposite ends index-)bymeans of the valve E. The ports f f2 are vformed on each side of the bushing and on the side opposite the live-pressure passage, and located in a central or intermediate position is the exhaust-port f3 in direct communication with the exhaust-passage EX of ordinaryor preferred form. The passage leading from the port f to the upper end of the cylinder is a simple exterior channel or groove formed in the bushing and opening out at the of the cyl- IOO bottom of the same, while a similar channel not opening out at the bottom of the bushing is formed in communication with port f2 and adapted to register with the mouth or opening g ot the channel g', leading down in the wall of the casing to a point below the upper end ot the piston ll when at the outer extreme of its movement, at which point it is adapted to register with the elongated mouth or opening H of the channel H2, formed in and opening out at the bottom of the piston. Instead of passing into the piston this passage may, however, continue down in the casing, as indicated in dotted lines, Fig. b. The valve controlling the ports in the bushingbefore referred to is provided with three pis tons or partitions so to speak, forming between them two annular chambers adapted to alternately connect each of the ports f f2 with its pressure-supply port f and with the eXhaust-portj, and when the latter connection is made the portf at that end is covered and closed by the end piston or partition, as will be readily understood by those skilled in the art, such construction being well known at this day. For shifting the valve in the present instance pressure is taken from the live pressure channel F through a small branch channel formed in the exterior of the bushing to passage 7a2, formed in the wall of the easing and leading down to a point below the upper end of the piston when at the lower extreme of its movement, where it is provided with ports 7:. 7a2, which are adapted to register with a single channel formed in the piston itself, which connects said ports alternately with the passages 7c4 705, leading, respectively,to opposite ends of the bushing, or, more properly speaking, communicating with ports k6 37, respectively, which pass through the bushing at opposite ends to admit air for moving the valve. These ports 766 7t7,it will be noted particularly, do not pass through the bushing at the extreme ends but at a point slightly removed therefrom, thus forming a positive air-cushion for the valve at each extreme of its stroke and preventing anypossibilityof its pounding or striking the end of the casing violently.

The single passage or channel t, formed in the piston for connecting the ports 7s and 7s and 7,53 and 7u", respectively,is a simple drilled passage having three openings located in the same transverse plano, while the polts 7cL 795, with which the outside openings register, are located in transverse planes separated a distance equal to the length ot the stroke of the piston, which construction gives the alternate pressure at opposite ends of the valve. Corresponding to said passage, but above and below the same, are passages Z', which communicate with an exhaust-passage formed in the wall of the casing on the opposite side, where an elongated port r is formed, which is constantly open to exhaust. These passages Z communicate alternately with the passages 7u L5, respectively, to exhaust pressure from the end of the valve opposite to the end taking pressure. The piston is kept from rotating by a spline working in the groove 701", thus keeping the ports and passages in proper alignment.

Referring particularly to Figs. t and 6, it will be seen that the ports 7o', 7c3, 7u, and 705 are round, and they are formed by simply drilling through the casing from the outside, and then plugging the outer ends of the holes, while the corresponding ports b 7) in the piston are somewhat elongated and narrowed toward each end, and hence open the communication with and from the valve gradually or in a relatively gradual manner. This gradual opening of the ports starts and stops the valve gradually, and the result is accomplished by a structure costing practically no more than if the holes were simply drilled, no inside cutting of the casing being required.

It will be noted that the whole instrument is simple, inasmuch as the difficult and complicated. passages are entirely in the exterior of the bushing, enabling the ports to be accurately formed and finished without the nece.. sity of extreme accuracy in making the borings for the passages in the casing.

ln the preferred construction the bushing and valve lit within the screw-threaded prolongation of the casing, onto which the cappiece screws, and the cover or closure d for the upper end of the bushing is held in place by said cap-piece, although it is obvious that a screw-thread or other fastening means may be employed to advantage in some instances.

.An annular throttle S, as shown, may be employed for controlling the exhaust-passage with a stop-pin for limiting its movement and a disk friction-spring S bearing on its side to prevent accidental movement. The eX- haust from the valve may pass into the main exhaust, as has been heretofore proposed, without departing from my invention in the least.

The location of the Valves and piston in alignment is of the utmost importance, both because of the advantages pointed out in manufacturing and because it practically does away with lateral vibration, the jar or shock occasioned by the valve in the present arrangement being exerted in the same direction as that occasioned by the piston and being so light is practically unnoticed. By arranging the ports to cut off at the proper point to cushion the return stroke of the hammer and the movement of the valve in both directions, as will be at once understood by those skilled in the art, all injurious vibra tion of the tool is practically annihilated, thus overcoming one of the chief objections to handling this class of instrument.

Having thus described my invention, what l claim as new isl. In a pneumatic tool, the combination, with the casing having the cylinder and valvechest formed in alignment therein and separate from each other, of the tool-stock, the

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piston, the valve controlling the ports and passages leading from the valve-chest to the cylinder, and the passages leading to opposite ends of the valve controlled by the piston, substantially as described. Y

2. In a pneumatic tool, the combination, with the casing having the central longitudinal opening therein and the piston mounted in the lower portion of said opening, of the valve-bushing mounted in the upper end of said opening, separating the valve-chest from the cylinder and having the ports or channels formed in the exterior thereof, the valve carried by said bushing, the tool-stock, and the cap-sections, substantially as described.

3. In a pneumatic tool, the combination, with the casing having the central longitudinal opening of smaller diameter at one end, the tool-stock and cap-section, substantially as described, of the valve-bushing mounted in the smaller end of said longitudinal opening and separating the Valve-chest and cylinder, the valve carried by the bushing, the piston mounted in the larger end of said opening, and the ports or passages controlled by the valve for admitting and exhausting pressure to opposite ends of the piston, substantially as described.

4. In a pneumatic tool such Aas herein described, the combination, with the casing containing the cylinder, the piston, and toolstock, of the valve-bushing carried by said casing in alignment with the cylinder at one end thereof and having longitudinal channels formed in its exterior communicating with channels leading to opposite ends of the cylinder, and a valve in said bushing controlling the admission and exhaust of pressure to opposite ends ot' the cylinder, respectively, substantially as described.

5. In a pneumatic tool, the combination, with the casing having the central longitudinal opening of smaller diameter at one end than at the other and the Vpiston mounted in the larger end of said opening, of the Valve-bushing mounted in the smaller end of said opening, with the longitudinal passages formed in its exterior, one of said passages opening out at the upper end and constituting a live-pressure passage, another of said passages opening out at the lower end and constituting the passage to the upper end of the cylinder, while an intermediate passage communicates with a passage in the casing leading to the lower end of the cylinder, and a valve controlling said passages, substantially as described.

6. In a pneumatic tool adapted to be held in the operators hand,the combination, with the casing having the cylinder and valve in alignment with ports and passages, substantially as described, and the piston and valve,

of the cap inclosing the end of the casing,-

having the entrace-port in line with the valve, the point-section, and the tool-stock movably held in said point-section independent ot' the piston, substantially as described.

7. In a pneumatic tool, the combination, with the casing having the cylinder and valvebox formed therein, with the ports for conveying pressure and exhaust from opposite ends of the valve opening into the valve-box at a point slightly removed from the ends of the same, and the ports and passages leading from the valve-box to opposite ends of the cylinder, of the Valve mounted in the valvebox for controlling said last-mentioned ports and passages and the piston controlling the passages leading to the ends of the valve-box, substantially as described.

8. In a pneumatic tool, the combination, with the valve and piston, of their inclosing casing having the ports controlled by the piston for operating the valve opening into the valve-box at a point slightly removed from the ends, whereby cushions are formed for the Valve at each extreme of its movement, substantially as described.

9. In a pneumatic tool, the combination, with the casing having the independent valve and piston, of the single supply-passage having two ports and the passages leading to each end of the valve formed in the casing, the single passage in the piston for alternately connecting the pressure and each passage leading to the valve and the passage in the piston open to exhaust and alternately communicating with said last-mentioned passages, substantially as described.

l0. In a pneumatic tool, the combination, with the casing or cylinder with air-passages leading from the air-port to each end of the cylinder through the valve-box and from the air-port to the cylinder at an intermediate point and from an intermediate point to opposite ends of the valve-box, said intermediate ports being and formed from the outside, of the valve-box, the valve Working therein and controlling the passages leading to the ends of the cylinder, and the piston working in the cylinder and having air-passages for connecting the intermediate ports in the cylinder leading to the valve, the Ymouths or ports ot' said passages in the piston being elongated and narrowed toward each end, whereby the valve is started and arrested gradually, substantially as described.

DANIEL DRAWBAUGH. Witnesses:

ERNEST MAIX, JNO. A. HERMAN.

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